Leg elimination strategy for hatch pattern

ABSTRACT

A scanning technique for the additive manufacturing of an object. The method comprises the irradiation a portion of a given layer of powder to form a fused region using an energy source. When forming an object layer by layer, the irradiation follows a first irradiation pattern at least partially bounded by a stripe region. When forming the first fused region using a first irradiation pattern a first series of solidification lines are formed, at angle other than 90° with respect to a substantially linear stripe region boundary. A series of second solidification lines are formed that intersecting the end of the first solidification line at a first angle other than 0° and 180° with respect to the first solidification line. A third series of solidification lines are formed that are substantially parallel to a first series of solidification lines and intersect one of the second solidification lines.

INTRODUCTION

The disclosure relates to an improved method of producing componentsusing an additive manufacturing technique. The disclosure provides animproved method of producing components, some of examples of whichcomprise: improved microstructure, decreased manufacturing time,decreased cost, decreased waste of materials. In particular, thedisclosure relates to a process of scanning a radiation beam (i.e.,laser or e-beam) during a powder-based additive manufacturing buildprocess.

BACKGROUND

Additive manufacturing (AM) techniques may include electron beamfreeform fabrication, laser metal deposition (LMD), laser wire metaldeposition (LMD-w), gas metal arc-welding, laser engineered net shaping(LENS), laser sintering (SLS), direct metal laser sintering (DMLS),electron beam melting (EBM), powder-fed directed-energy deposition(DED), and three dimensional printing (3DP), as examples. AM processesgenerally involve the buildup of one or more materials to make a net ornear net shape (NNS) object in contrast to subtractive manufacturingmethods. Though “additive manufacturing” is an industry standard term(ASTM F2792), AM encompasses various manufacturing and prototypingtechniques known under a variety of names, including freeformfabrication, 3D printing, rapid prototyping/tooling, etc. AM techniquesare capable of fabricating complex components from a wide variety ofmaterials. Generally, a freestanding object can be fabricated from acomputer aided design (CAD) model. As an example, a particular type ofAM process uses an energy beam, for example, an electron beam orelectromagnetic radiation such as a laser beam, to sinter or melt apowder material and/or wire-stock, creating a solid three-dimensionalobject in which a material is bonded together.

Selective laser sintering, direct laser sintering, selective lasermelting, and direct laser melting are common industry terms used torefer to producing three-dimensional (3D) objects by using a laser beamto sinter or melt a fine powder. For example, U.S. Pat. No. 4,863,538and U.S. Pat. No. 5,460,758 describe conventional laser sinteringtechniques. More specifically, sintering entails fusing (agglomerating)particles of a powder at a temperature below the melting point of thepowder material, whereas melting entails fully melting particles of apowder to form a solid homogeneous mass. The physical processesassociated with laser sintering or laser melting include heat transferto a powder material and then either sintering or melting the powdermaterial. Electron beam melting (EBM) utilizes a focused electron beamto melt powder. These processes involve melting layers of powdersuccessively to build an object in a metal powder.

AM techniques, examples of which are discussed above and throughout thedisclosure, may be characterized by using a laser or an energy source togenerate heat in the powder to at least partially melt the material.Accordingly, high concentrations of heat are generated in the finepowder over a short period of time. The high temperature gradientswithin the powder during buildup of the component may have a significantimpact on the microstructure of the completed component. Rapid heatingand solidification may cause high thermal stress and cause localizednon-equilibrium phases throughout the solidified material. Further,since the orientation of the grains in a completed AM component may becontrolled by the direction of heat conduction in the material, thescanning strategy of the laser in an AM apparatus and technique becomesan important method of controlling microstructure of the AM builtcomponent. Controlling the scanning strategy in an AM apparatus isfurther crucial for developing a component free of material defects,examples of defects may include lack of fusion porosity and/or boilingporosity.

FIG. 1 is schematic diagram showing a cross-sectional view of anexemplary conventional system 110 for direct metal laser sintering(DMLS) or direct metal laser melting (DMLM). The apparatus 110 buildsobjects, for example, the part 122, in a layer-by-layer manner (e.g.layers L1, L2, and L3, which are exaggerated in scale for illustrationpurposes) by sintering or melting a powder material (not shown) using anenergy beam 136 generated by a source such as a laser 120. The powder tobe melted by the energy beam is supplied by reservoir 126 and spreadevenly over a build plate 114 using a recoater arm 116 travelling indirection 134 to maintain the powder at a level 118 and remove excesspowder material extending above the powder level 118 to waste container128. The energy beam 136 sinters or melts a cross sectional layer (e.g.layer L1) of the object being built under control of the galvo scanner132. The build plate 114 is lowered and another layer (e.g. layer L2) ofpowder is spread over the build plate and object being built, followedby successive melting/sintering of the powder by the laser 120. Theprocess is repeated until the part 122 is completely built up from themelted/sintered powder material. The laser 120 may be controlled by acomputer system including a processor and a memory. The computer systemmay determine a scan pattern for each layer and control laser 120 toirradiate the powder material according to the scan pattern. Afterfabrication of the part 122 is complete, various post-processingprocedures may be applied to the part 122. Post processing proceduresinclude removal of excess powder, for example, by blowing or vacuuming,machining, sanding or media blasting. Further, conventional postprocessing may involve removal of the part 122 from the buildplatform/substrate through machining, for example. Other post processingprocedures include a stress release process. Additionally, thermal andchemical post processing procedures can be used to finish the part 122.

The abovementioned AM processes is controlled by a computer executing acontrol program. For example, the apparatus 110 includes a processor(e.g., a microprocessor) executing firmware, an operating system, orother software that provides an interface between the apparatus 110 andan operator. The computer receives, as input, a three dimensional modelof the object to be formed. For example, the three dimensional model isgenerated using a computer aided design (CAD) program. The computeranalyzes the model and proposes a tool path for each object within themodel. The operator may define or adjust various parameters of the scanpattern such as power, speed, and spacing, but generally does notprogram the tool path directly. One having ordinary skill in the artwould fully appreciate the abovementioned control program may beapplicable to any of the abovementioned AM processes. Further, theabovementioned computer control may be applicable to any subtractivemanufacturing or any pre or post processing techniques employed in anypost processing or hybrid process.

The above additive manufacturing techniques may be used to form acomponent from stainless steel, aluminum, titanium, Inconel 625, Inconel718, Inconel 188, cobalt chrome, among other metal materials or anyalloy. For example, the above alloys may include materials with tradenames, Haynes 188®, Haynes 625®, Super Alloy Inconel 625™, Chronin® 625,Altemp® 625, Nickelvac® 625, Nicrofer® 6020, Inconel 188, and any othermaterial having material properties attractive for the formation ofcomponents using the abovementioned techniques.

In the abovementioned example, a laser and/or energy source is generallycontrolled to form a series of solidification lines (hereinafterinterchangeably referred to as hatch lines, solidification lines andraster lines) in a layer of powder based on a pattern. A pattern may beselected to decrease build time, to improve or control the materialproperties of the solidified material, to reduce stresses in thecompleted material, and/or to reduce wear on the laser, and/orgalvanometer scanner and/or electron-beam. Various scanning strategieshave been contemplated in the past, and include, for example, chessboardpatters and/or stripe patterns.

One attempt at controlling the stresses within the material of the builtAM component involves the rotation of stripe regions containing aplurality of adjoining parallel vectors, as solidification lines, thatrun perpendicular to solidification lines forming the boundaries of thestripe region. for each layer during an AM build process. Parallelsolidification lines, bounded by and perpendicular to a stripe, arerotated for each layer of the AM build. One example of controlling thescanning strategy in an AM apparatus is disclosed in U.S. Pat. No.8,034,279 B2.

FIGS. 2 and 3 represent the abovementioned rotating stripe strategy. Thelaser is scanned across the surface of a powder to form a series ofsolidification lines 213A, 213B. The series of solidification lines forma layer of the build and are bound by solidification lines in the formof stripes 211A, 212A and 211B, 212B that are perpendicular to thesolidification lines 213A and 213B forming the boundaries of each striperegion. The stripe regions bounded by solidification lines 211A and 212Aform a portion of a larger surface of the layer to be built. In forminga part, a bulk of the part cross section is divided into numerous striperegions (regions between two solidified stripes containing transversesolidification lines). A stripe orientation is rotated for each layerformed during the AM build process as shown in FIGS. 2 and 3. A firstlayer may be formed with a series of parallel solidification lines 213A,in a stripe region, formed substantially perpendicular to and bounded bysolidified stripes 211A. In a subsequent layer formed over the firstlayer, the stripes 211B are rotated as shown in FIG. 3. By creating astripe boundary for the solidified lines 213A and 213B through a set ofsolidified stripes 211B and 212B that are rotated with respect to theprevious layer, solidification lines 213B, which are be formedperpendicular to and are bounded by stripes 211B are also be rotatedwith respect the solidification lines 213A of the previous layer.

As shown in FIGS. 4 and 5, a built AM component includes a plurality oflayers 215, 216, 217. When built using the abovementioned strategy, afirst layer 217 may be divided by software into several stripe regionsbounded by, stripes 257 and 277 formed as solidification lines. Thestripes 257 and 277 may form a boundary for individually formed paralleladjoining vectors or solidification lines 267. The surface of the partincludes a plurality of stripes covering the surface to be built. Asshown in FIG. 5, each stripe region is bounded by solidified stripes 257and 277 in layer 217 form a boundary for a series of parallel solidifiedlines 267. The parallel solidification lines 267 are perpendicular tothe solidified stripe boundaries 257 and 277. The stripes are orientedat a first angle in layer 217 with the perpendicular solidificationlines 267 being formed substantially perpendicular to the stripes 257and 277. The stripe region bound by solidified stripes 256 and 257 on asecond layer 216 are angled with respect to the solidified stripeboundaries 257 and 277 on previous layer 217. Accordingly,solidification lines 266 that run perpendicular to solidified stripes256 and 276 are also be angled with respect to the solidification lines267 on previous layer 217. As the build progresses, a next layer havingstripes 265 and 275 on a third layer 215 are angled with respect tostripes 257 and 277 on layer 217; and stripes 256 and 276 on layer 216.

Even with the abovementioned rotating stripe strategy, the need existsto further create variance in each layer. By employing the variousembodiments disclosed, build efficiency can be further increased bypreventing unnecessary jumps of the energy source, preventingunnecessary on/off transitions of the laser and/or improving controland/or efficiency of heat buildup within the layer. Further themicrostructure of the part can be altered by controlling the pattern ofstripe regions and solidification lines within the stripe region.

SUMMARY OF THE INVENTION

One challenge associated with laser based AM is producing a desired meltpattern in the powder while maintaining a desired speed of the buildprocess. Slowing of the build process and/or inaccuracies in the meltpattern result, for example, when a laser is turned on and/or off tooearly or late at the beginning and/or end of a hatch line. Turning alaser on too early may result in a burn-in effect where the melt pool islonger than the desired length of the hatch. Further, the buildup ofheat within the powder and fused material during a build is a concern,as various material defects may occur if too much heat is built up inthe material during an AM process and/or if insufficient heat is builtup to properly fuse the powder.

The disclosure relates to an improved scanning strategy, having a hatchpattern for scanning a laser during an AM build process. Whencontrolling the laser during the build process according to oneembodiment, an alternating hatch pattern is used to form solidificationlines on each layer so as to improve the microstructure of the completedcomponent. In one aspect, a first layer is formed by scanning a laseracross the surface of the powder to form at least partially meltedsolidification lines, wherein each line is scanned and formed as asolidification line forming two angled segments of a triangle. In otherwords, a solidification line is formed along a first liner path and asecond linear path and the first and second linear paths are angled withrespect to one another. The first and second linear paths of the laserscan and subsequently formed solidification lines may be containedwithin a stripe region forming a portion of the component being built.Once the series of solidification lines are formed on the layer, asubsequent layer of powder is added on top of the previously solidifiedscan lines; and a second series of solidification lines are formed as afirst linear path and a second linear path, wherein the first linearpath is angled with relation to the second liner path. Further, theabovementioned angle formed between the first linear path and secondlinear path may be varied for each subsequent layer; so that nosubsequent layer has the same angle between the first linear path andthe second linear path, thereby improving build efficiency and/or thebalance of stresses imparted in the finished solidified component formedusing the AM process.

By dividing up areas of the surface to be scanned as described below,further variance between layers can be achieved during an AM buildallowing for increased control of the microstructure of the completedcomponent. Build efficiency can also be further increased by preventingunnecessary jumps of the energy source, preventing unnecessary on/offtransitions of the laser and/or by improving control and/or efficiencyof heat buildup within the layer being formed and/or the layers of thebuild. In the case of multiple lasers and/or energy sources being used,the disclosed scanning scheme may be used to further improve the AMbuild by employing various strategies for the use of multiple energysources (e.g. lasers and/or electron-beams).

When forming a series of the abovementioned first solidification lineand second solidification lines. The possibility of a high energydensity region may occur near the end of a stripe or near the end ofcontour of the component, in order to balance the heat distributionthroughout the layer, a third series of solidification lines may beformed that are substantially parallel to a first series ofsolidification lines and intersect one of the second solidificationlines. By forming the third series of solidification lines, the distanceover which the energy source is scanned is increased, thus preventing ahigh concentration of heat within a certain region of the componentbeing built. By dividing up areas of the surface to be scanned asdescribed below, further variance between layers can be achieved duringan AM build allowing for increased control of the microstructure of thecompleted component. Build efficiency can also be further increased bypreventing unnecessary jumps of the energy source, preventingunnecessary on/off transitions of the laser and/or by improving controland/or efficiency of heat buildup within the layers of the build. In thecase of multiple lasers and/or energy sources being used, the disclosedscanning scheme may be used to further improve the AM build by employingvarious strategies for the use of multiple energy sources (e.g. lasersand/or electron-beams).

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and constitute apart of this specification, illustrate one or more example aspects ofthe present disclosure and, together with the detailed description,serve to explain their principles and implementations.

FIG. 1 is a side view and top view diagram of a conventional additivemanufacturing technique used to form at least part of a component;

FIG. 2 is a top view depicting a conventional hatch and stripe patternused to form at least a part of a component;

FIG. 3 is a top view depicting a conventional hatch and stripe patternused to form at least a part of a component;

FIG. 4 is a perspective view, depicting example layers of componentbuild during a conventional AM process;

FIG. 5 is a top view of the individual layers shown in FIG. 4, depictinga conventional hatch and stripe pattern used to form at least a part ofa component;

FIG. 6 is a top view depicting a hatch and stripe pattern used to format least a part of a component in accordance with one aspect of thedisclosure;

FIG. 7 is a top view depicting a hatch and stripe pattern used to format last a portion of a component in accordance with one aspect of thedisclosure;

FIG. 8 is a perspective view, depicting example layers of componentbuild during an AM process in accordance with one aspect of thedisclosure;

FIG. 9 is a top view of the individual layers shown in FIG. 8, depictinga hatch and stripe pattern used to form at least a part of a componentin accordance with one aspect of the disclosure;

FIG. 10 is a top view depicting a hatch and stripe pattern and anexample path of the energy source in accordance with one aspect of thedisclosure;

FIG. 11 is a top view depicting a hatch and stripe pattern used to format least a part of a component in accordance with one aspect of thedisclosure;

FIG. 12 is a top view depicting a hatch and stripe pattern used to format least a part of a component in accordance with one aspect of thedisclosure;

FIG. 13 is a perspective view, depicting example layers of componentbuild during an AM process in accordance with one aspect of thedisclosure;

FIG. 14 is a top view of the individual layers shown in FIG. 13,depicting a conventional hatch and stripe pattern used to form at leasta part of a component in accordance with one aspect of the disclosure;

FIG. 15 is a top view depicting an example leg elimination hatch andstripe pattern and an example path of the energy source in accordancewith one aspect of the disclosure;

FIG. 16 is a top view depicting an example hatch and stripe pattern andan example path of the energy source using an example dwell path inaccordance with another aspect of the disclosure.

DETAILED DESCRIPTION

While the aspects described herein have been described in conjunctionwith the example aspects outlined above, various alternatives,modifications, variations, improvements, and/or substantial equivalents,whether known or that are or may be presently unforeseen, may becomeapparent to those having at least ordinary skill in the art.Accordingly, the example aspects, as set forth above, are intended to beillustrative, not limiting. Various changes may be made withoutdeparting from the spirit and scope of the disclosure. Therefore, thedisclosure is intended to embrace all known or later-developedalternatives, modifications, variations, improvements, and/orsubstantial equivalents.

When using any of the abovementioned AM techniques to form a part by atleast partially melting a powder, a scan of the laser across the powdermaterial, in a raster scan fashion is used to create hatch scans(hereinafter referred to interchangeably as hatch scans, rasters, scanlines, or solidification lines). During an AM build, the abovementionedsolidification lines are used to form the bulk of a part cross section.Contour scans, may further be used to outline the edges of the partcross section. During a raster scan process, the energy source or laseris turned on, increased in power and/or focused in regions where a solidportion of the AM build is desired, and switched off, defocused, and/ordecreased in power where melt formation of the object's cross section inthat layer are not desired. During a raster scan process, at leastpartially melting of powder and formation of solidification is repeatedalong adjacent solidification lines, for example, to form a singlemelted and fused cross section of the object to be built, while thecontour scans create a discrete border or edge of the part. In theexample AM apparatus using a powder bed, once the melt formation of onecross section of the object being built is completed, the apparatuscoats the completed cross-sectional surface with an additional layer ofpowder. The process is repeated until the object is complete.

In the aforementioned and subsequent embodiments, the laser and/orenergy source is controlled to form a series of solidification lines ina layer of powder using a pattern for at least the following reasons; todecrease build time, to control the heat buildup within the powderand/or to increase the efficiency of the build, to improve and/orcontrol the material properties of the solidified material, to reducestresses in the completed material, and/or to reduce wear on the laserand/or galvanometer scanner.

FIGS. 6 and 7, represent the scan pattern of one embodiment, wherein alaser is used to form an angled scan pattern forming solidificationlines (e.g. 311 and 312) within a stripe region bounded one or morestripes 308 and/or 309. One of or both of the stripes 308 and/or 309 mayeither be an imaginary boundary and/or may be formed as a solidificationline. For example as shown in FIG. 10, the laser or a plurality oflasers may be focused, increased in power and/or turned on while withinthe stripe region having width 314 and having imaginary and/or realboundaries 315 and/or 316; accordingly, while a specific stripe regionis being formed, solidification lines are only formed within a striperegion bounded by stripe boundaries 315 and 316. When the path of thelaser or plurality of lasers are scanned outside of the boundaries ofthe stripe region (e.g. portions 401 and 405) the irradiation source isturned off, defocused and/or decreased in power so that melting andsolidification of the powder does not occur. As an alternative, thestripe boundaries 315 and/or 316 may also be at least partially meltedand solidified by a laser or irradiation source and formed assolidification lines either before, after, or during a scan andsolidification process within the stripe region.

FIGS. 6 and 7 represent the angled solidification lines which may beformed within each stripe region in accordance with one aspect of thedisclosure. The solidification line pattern may be selected to controland/or improve the stresses and microstructure within the materialduring a build process and/or to improve efficiency of the buildprocess. The pattern shown in FIGS. 6-10 is one example of at leastpartially melted and subsequently solidified powder that has been fusedusing an irradiation source to form solidification lines. The scanpattern may be contained within a stripe region bounded by a firststripe boundary 308 and may further be bounded by a second stripeboundary 309 that is substantially parallel to the first stripe boundary308 and located a distance 310 from the first stripe. It is noted thatthe disclosed pattern, or any of the patterns described below, may alsocover a portion and/or entire span of the cross-section of the layer ofthe part being formed and each layer may be formed by forming thepattern within stripe regions, over a span of the entire surface, or anycombination of the two. By forming an angled scan pattern, an increasein the variance between layers can be achieved over the abovementionedrotating stripe scheme resulting in a build process that is moreefficient and allowing further tailoring of the microstructure andmaterial properties of the completed component.

In one embodiment, for each layer formed during the AM build process, afirst portion of a first layer is formed with solidification lines 311Aformed at an a angle other that 90° with relation to the boundary 308 ofthe stripe region; the solidification lines 311 may be contained orbounded by two or more stripe boundaries (which may hereinafter beinterchangeably referred to as a stripe and/or boundary stripe). Thestripes may have a stripe boundary spacing 310. The solidification lines311 of each layer includes a series of first parallel solidificationlines 311A beginning at and/or ending at stripe boundary 308 and asecond set of solidification lines 311B beginning and/or ending at theopposite stripe boundary 309 of the stripe region. Accordingly, whenforming the solidification lines, the laser and/or energy sourcescanning vector changes directions (e.g. from 311A, and then forms asecond solidification line 311B, wherein the second solidification line311B is angled θ_(A1) with respect to first solidification line 311A).In other words, the first series of solidification lines 311A form anincident angle, represented by θ_(A1) with respect to the second seriesof solidification lines 311B.

In a subsequent layer formed over the first layer, an example of whichis shown in FIG. 7, at least a first portion of a second layer is formedwith solidification lines 312 formed within a stripe region having width314 at an a angle other that 90° with relation to, and bounded by atleast one boundary 315 and/or 316. The stripe region spacing 314 havingat least two stripe boundaries 315 and/or 316 may be the same as ordifferent from the stripe spacing 310 of a previous layer or asubsequent layer (not shown). Further, the solidification lines 312 ofthe layer may include a series of third parallel solidification lines312A beginning at and/or ending at the stripe region boundary 316. Whenforming the raster scan in the exemplary layer shown in FIG. 7, thelaser and/or energy source may change directions and form a fourthseries of solidification lines 312B, wherein the fourth series ofsolidification lines 312B are angled with respect to the third series ofsolidification lines 312A. The third series of solidification lines 312Aare formed at an incident angle θ_(A2) with respect to the fourth seriesof scan vectors 312B. Angles θ_(A1) and/or θ_(A2) may be varied so thatno subsequent or previous layer has an angle that is the same. Further,in one aspect the difference between θ_(A1) and θ_(A2) may be 10° orgreater.

FIGS. 8-10, represent an AM component comprising built by thesolidification of a plurality of layers 415, 416, 417, and 418 inaccordance with one embodiment. When built using any of theabovementioned AM processes, a first layer 418 may be divided by theabovementioned software into several stripe regions bounded by stripeboundaries. For example, stripe boundaries 465, 475, and 476 may form atleast one boundary for transversely formed solidification lines. Thestripe boundaries 465 and 475 may form a boundary for individuallyformed solidification lines 455. As an example, each solidification lineis formed by at least partially melting portions 402 and 403 as a firstsubstantially linear solidification line and a second substantiallylinear solidification line respectively. Solidification lines 402 and403 may be in close proximity to the next set of formed solidificationlines 412 and 413. In at least one embodiment, if the laser and/orenergy source melts the powder corresponding to each of portions 402,403, 412, and 414 in succession, the portions 402, 403, 412, and 414 mayfuse together. For example, when forming portions 402, 403, 412, and 414a laser and/or energy source may adjusted to control the amount ofpowder melted along a solidification line; accordingly, a melting widthand depth of each solidification line may be controlled. When the lasermelts powder corresponding to solidification line 412, the material inthe portion 402 may not have cooled and the thin line of powder betweenthe portion 402 and the portion 412 may at least partially melt. Themolten material in a solidification line 402 may fuse with the moltenmaterial in solidification line 412 and the molten material insolidification line 413 may fuse with the molten material insolidification line 403. The energy source and/or laser may also becontrolled so that the heat radiating from the solidification line 402,and solidification line 412 may cause the thin line of powder betweensolidification lines 402 and/or 403 and solidification lines 412 and/or413 to sinter together without melting. Further, the scanning of theenergy source and/or laser to form, for example, solidification line 402and solidification line 412 may cause the thin line of powder betweenthe solidification lines 402 and/or 403 and solidification lines 412and/or 413 to remain unfused without sintering and/or melting.

When forming the individual solidification lines 402, 403, 412, and 413,in an example embodiment using a laser as the energy source, agalvanometer scanner may guide the laser over a path starting at 401,and continue subsequently to portions 402, 406, 404, 408, 403, 405, 413and 412. As shown in FIG. 10, the energy source may be turned off,decreased in power, and/or defocused (hereinafter interchangeablyreferred to as skywriting and/or skywritten) over the path 408, 404,406, the. It is noted that while FIG. 10 shows path 408, 404, 406between solidification lines 402 and 403, a similar path may be followedby the energy source guiding portion for each subsequent series ofsolidification lines (e.g. 413 and 413, for example). As an alternative,the galvanometer scanner or other energy source guiding mechanism mayalso guide the energy source (e.g. laser) over a path starting at 401and continue subsequently to portions 402, 414, 403, 405, 413 and 412,in this alternative, the energy source may form a solidification line402 and continuously form a curved solidification portion 414 andsolidification line 403. It is noted that while FIG. 10 shows thealternative curved solidification path 414 between solidification lines402 and 403, a curved solidification path, such as shown in reference414 may be followed by the energy source guiding portion for eachsubsequent series of solidification lines (e.g., 413 and 413, forexample) thereby connecting each of the solidification lines with acurved solidification path instead of forming a point (e.g. theintersection between solidification lines 402 and 403) at theintersection of each set of solidification lines. As yet anotheralternative, solidifications lines 402 and 403 may be formedcontinuously without the energy source being turned off, defocusedand/or decreased in power. Forming solidification lines 402 and 403continuously, without any skywriting (e.g. 406, 404, and 408) or withoutforming a curved solidification portion (e.g. 414) between the twosolidification lines may be most advantageous when the incident anglebetween the each solidification line (e.g. 402 and 403 or 413 and 412 issufficiently large. In one example, a set of solidification lines (e.g.402 and 403) are formed continuously, without skywriting (e.g. 408, 404,and 406) or forming a curved solidification portion (e.g. 414) betweenthe two solidification lines when the incident angle between thesubsequent solidification lines is greater than 120°. Further, the twosegments may be formed continuously, without skywriting or forming acurved solidification portion (e.g. 414) between the two solidificationlines, when the incident angle between the two subsequent solidificationlines is greater than 150°. When forming the abovementioned portions,the laser is also turned off, defocused and/or decreased in power suchthat skywriting occurs in portions 401 and 405, so when formingsolidification lines within the stripe region bounded by stripeboundaries 315 and/or 316, the laser and/or energy source only suppliesenough energy to the powder to at least partially melt the powder withinthe stripe region. It is noted the abovementioned scan pattern is notlimited to one energy and/or laser source, and may be performed by aplurality of energy and/or laser sources. For example, a first laser maysolidification lines 402 and 403, and a second laser may formsolidification lines 412 and 413. Further, it is noted that each of theabovementioned alternative paths (e.g. skywrite 404, curvedsolidification path 414 and/or continuously formed solidification lineswithout a curved solidification path or skywrite between two sets ofangled solidification lines) may be formed either consistentlythroughout the stripe, layer and/or the build, or the abovementionedpaths may be used in any combination either within a stripe, within abuild layer, and/or throughout the build.

FIGS. 8 and 9, represent the process of building a component using an AMtechnique in accordance with one embodiment. At least a portion of acomponent built using an AM technique, an example of which is shown inFIG. 8, comprises a plurality of at least partially fused layers 415,416, 417, and 418. A first layer 418 may be divided by theabovementioned software into several stripe regions bounded by, forexample, stripe boundaries 435, 436, 445, 446, 465, 475, and 476. Thestripe regions in layer 418, having a width 314D, form a boundary forseries of individual scan portions formed as solidification lines 458Aand 458B, for example. Each solidification line is formed at an a angleother that 90° with relation to stripe boundaries 435 and 445 and iscontained within the stripe region. A first solidification line 458Aformed on layer 418 may be substantially linear and may form an incidentangle θ₁ with respect a second substantially linear solidification line458B. As shown in FIG. 10 the energy source and/or laser path may followa first linear path to form solidification line 458A and may changedirection to a second linear path to form a second portion of thesolidification line 458B such that the laser forms portions 458A and458B along the surface of the powder. Further, while the exemplaryfigures show solidification lines 458A and 458B forming an angle havinga point, the abovementioned raster scans may form an angle having afilleted or curved transition (e.g. as shown in FIG. 10 reference 414)between solidification lines 458A and 458B, for example. The striperegion having a width 314D may further be filled in with a plurality ofsolidification lines parallel to, for example, portions 458A and 458B(e.g. as shown in FIG. 10).

In a next layer 417 of the AM build, a subsequent layer of powder isdistributed over the surface of layer 418. Based on the desired geometryof the AM part being built, layer 417 may be divided into a series ofstripe regions having a stripe width 314C. The stripe width 314C may bethe same as or different from stripe width 314D of the previous layer.Layer 417 may include a series of solidification lines 457A and 457Bwhich are contained in each stripe region. Each stripe region may befilled with repeating solidification lines 457A and 457B which areformed at an a angle other that 90° with relation to, and bounded bystripe boundaries 436 and 446. For example, one specific solidificationline 457A may be substantially linear and may form an angle θ₂ withrespect to a continuously formed substantially linear solidificationline 457B. Angle θ₂ of layer 417 may be different from angle θ₁ of layer418, and may be varied by 10° or greater from θ₁ of layer 418 or any ofthe previous or the immediately subsequent layers. The energy sourceand/or laser path may form the solidification line 457A and changedirection to form a second portion of the solidification line 457B; thelaser may form portions 457A and 457B continuously as shown in theexample shown in FIG. 10. The stripe region having a width 314C mayfurther be filled in with a plurality of solidification lines parallelto, for example, portions 457A and 457B (e.g. as shown in FIG. 10).

Subsequent layers of the AM build may be formed using the abovementionedmethods. For example, layers 416 and 417 may be divided up into striperegions based on the desired geometry of the AM build. As stated above,the energy source and/or laser may form a solidification lines havingangles θ₃ and θ₄, which may be varied for each subsequent layer.Further, the angle with respect to each stripe boundary (e.g. 465, 475and 476) may be varied for each additional layer. And the stripe width314B and 314A may be the same or different for each subsequent layer. Asmentioned above, the angles between a first solidification line and asecond solidification line θ₃ in layer 416 and θ₄ in layer 415 may varyby 10° or more for each subsequent layer.

Further, it is understood that the angle with respect to the stripeboundary for each layer (and the stripe width) may be varied for eachlayer so that the angle of the solidification lines is varied for eachlayer and the angle θ between first and second portion of eachsolidification line may be kept constant. It is also noted that thenumber of angles and solidification lines bounded by each stripe is notlimited to one angle and two portions of a solidification line, and mayinclude a solidification line having three or more portions all angledwith relation to one another. It may further be desirable to keep thestripe width, angle θ, and the raster hatch pattern constant between atleast two subsequent layers, so that the solidification lines are keptparallel between two or more layers. It is further noted that anycombination of the abovementioned features and methods may be usedtogether in an alternative scheme for building the component

FIGS. 11 and 12 represent a top view of a scanning and solidificationpattern according to another embodiment employing the abovementionedstrategies and a leg elimination strategy respectively. In certainportions of an AM build, depending on at least a geometry of the layerbeing built. It may be desirable to control the heat buildup within thepowder and/or in the solidification lines formed on the layer of powder.As shown in FIG. 11, when the forming a series of solidification lines(eg. 610 and 620) within a stripe region bounded by stripe boundaries601 and 602, solidification lines which may be formed within each striperegion in accordance with one aspect of the disclosure. Thesolidification line pattern may be selected to control and/or improvethe stresses and microstructure within the material during a buildprocess and/or to improve efficiency of the build process. The patternshown in FIG. 11 is one example of at least partially melted andsubsequently solidified powder that has been fused using the laser toform solidification lines. The scan pattern may be contained within astripe region bounded by a set of boundary stripes 601 and 602. Further,the stripe region may be bounded by a contour scan, the end of thecomponent to be built and/or a stripe boundary 603 (which will bereferred to throughout the disclosure as a stripe boundary). Whenfilling in the stripe region with solidification lines having firstportions 610 and second portions 620 angle with relation to one anothera high energy density portion 601 may be formed due to the shorter spansof the solidification lines near a stripe boundary 603. It may beadvantageous for even out the heat distribution within the build byemploying a leg elimination strategy, an example of which is shown inFIG. 12.

As shown in FIG. 12, at least a portion of a layer being at leastpartially melted during an AM build process may include a stripe regionbounded by stripe boundaries 611 and 612. The region may further bebounded by stripe 613. A first portion of a first layer is formed withsolidification lines 620A formed at an a angle other that 90° withrelation to the boundary 611 of the stripe region; the solidificationlines 610A may by contained or bounded by two or more stripe boundaries611, 612, and 613. The solidification lines 620 of each layer includes aseries of first parallel solidification lines 620A beginning at and/orending at stripe boundary 611 and a second set of solidification lines620B beginning and/or ending at the opposite stripe boundary 612 of thestripe region. Accordingly, when forming the solidification lines, thelaser and/or energy source scanning vector changes directions whileforming solidification line 620A, changes direction, and forms a secondsolidification line 620B, wherein the second solidification line 620B isangled with respect to the first solidification line 620A. In otherwords, the first series of solidification lines 620A form an angle withrespect to the second series of solidification lines 620B. Wheneverdesired and/or when it is determined that a high energy density portionof the build may occur, scanning of the laser and subsequentsolidification lines may be altered to form a third series ofsolidification lines 630, which are bounded and intersect one of thesecond series of solidification line 620B at a point (e.g. intersection792 in FIG. 15), for example. Further, when the third series ofsolidification lines 630 are no longer bounded by the secondsolidification lines 620B, the third series of solidification lines maybe continuously formed into an adjoining stripe region (e.g. portion 613formed beyond stripe boundary 612). The third series of solidificationlines 630B may also continue past boundary stripe 611 until boundarystripe 613 is reached.

FIGS. 13 and 14, represent several examples of the process of building acomponent using an AM technique in accordance with the abovementionedembodiment. At least a portion of a component built using an AMtechnique, an example of which is shown in FIG. 13, comprises aplurality of at least partially fused layers 717, 716, and 715. A firstlayer 717 may be divided by the abovementioned software into severalstripe regions bounded by, for example, stripe boundaries 711 and 712.The stripe regions in layer 717, having a width 714A, form a boundaryfor series of individual scan portions formed as solidification lines710A and 720A, for example. Solidification lines 710A and 720A areformed at an a angle other that 90° with relation to stripe boundaries711 and 712 and are contained within the stripe region. A firstsolidification line 710A formed on layer 717 may be substantially linearand may form an angle θ₁ with respect a second substantially linearsolidification line 720A. For example, the laser path may follow apattern as shown in FIG. 10; specifically, the energy source and/orlaser path may follow a first linear path to form solidification line710A and may change direction to a second linear path to form a secondportion of the solidification line 720A such that the laser formsportions 710A and 720A along the surface of the powder. However, whenthe laser scanning path is proximal to a portion a third boundary 713(e.g. a contour scan, the end of the component to be built and/or astripe boundary), a third solidification line 710B is formed. The thirdsolidification line 710B may be substantially parallel with asolidification line 710A, however solidification line 710 is formedusing a substantially linear laser path that does not change directionwhile at least partially melting the powder. In other words,solidification line 710B is formed from a first stripe boundary 711 to asecond solidification line 720A without changing direction.

Further, if a subsequent solidification line of the parallel series ofsolidification lines 710B is formed in a portion of the build where thelaser path does not intersect a second solidification line 720A, thelaser path may continue past stripe boundaries 711 and 712 and the buildmay begin in the next stripe region. For example, the solidificationlines 710B on layer 717 are bounded by 720A, when the path at whichsolidification lines 710B are formed no longer intersect 720A, thesolidification lines 710B continue past stripe boundary 712 and formsolidification line portion 782B in a bordering stripe region. The laserpath forming solidification line 782A then changes direction and forms asolidification line 783A which is angled with respect to solidificationline 782A. The build in the next stripe region can then continue usingany combination of the above series of angled solidification linesand/or linear leg elimination solidification lines.

In a next layer 716 of the AM build, a subsequent layer of powder isdistributed over the surface of layer 717. Based on the desired geometryof the AM part being built, layer 717 may be divided into a series ofstripe regions having a stripe width 414B. The stripe width 414B may bethe same as or different from stripe width 414A of the previous layer.Layer 417 may include a series of solidification lines 730A and 740Awhich are contained in each stripe region. Each stripe region may befilled with repeating solidification lines 730A and 740A which areformed at an a angle other that 90° with relation to, and bounded bystripe boundaries of a stripe region having width 714B. For example, onespecific solidification line 740A may be substantially linear and mayform an angle θ₂ with respect to a continuously formed substantiallylinear solidification line 730A. Angle θ₂ of layer 716 may be differentfrom angle θ₁ of layer 717, and may be varied by 10° or greater from θ₁of layer 717 or any of the previous or the immediately subsequentlayers. Similarly to the method above, the energy source and/or laserpath may form the solidification line 740A and change direction to forma second portion of the solidification line 730A and the stripe regionhaving a width 714B may be filled in with a plurality of solidificationlines parallel to, for example, portions 730A and 740A. However, whenthe laser scanning path is proximal to a portion a third boundary 714(e.g. a contour scan, the end of the component to be built and/or astripe boundary), a third solidification line 740B is formed. The thirdsolidification line 740B may be substantially parallel with asolidification line 740A, however solidification line 740B is formedusing a substantially linear laser path that does not change directionwhile at least partially melting the powder. In other words,solidification line 740B is formed from a stripe boundary to asolidification line 730A without changing direction. It is noted thatthe leg elimination strategy may be employed in a single stripe regionand/or over a single layer of the build and/or over the entire builddepending on the desired characteristics of the part. Any combination ofthe abovementioned and below discussed strategies may be employed incombination throughout the build process (e.g., one stripe may employ asubsequent stripe may use the abovementioned triangle hatch strategy).

When forming the triangular portion of the stripe region, as shown inFIGS. 15 and 16, for example, each solidification line may be formed byat least partially melting portions (703, 802) and (702, 803) as a firstsubstantially linear solidification line and a second substantiallylinear solidification line respectively. As shown, for example in FIG.16, the solidification lines 802 and 803 may be in close proximity tothe next set of formed solidification lines 812 and 813. In at least oneembodiment, if the laser and/or energy source melts the powdercorresponding to each of portions 802, 803, 812, and 814 in succession,the portions 802, 803, 812, and 81 may fuse together. For example, whenforming portions 802, 803, 812, and 813 a laser and/or energy source mayadjusted to control the amount of powder melted along a solidificationline; accordingly, a melting width and depth of each solidification linemay be controlled. When the laser melts powder corresponding tosolidification line 812, the material in the portion 802 may not havecooled and the thin line of powder between the portion 802 and theportion 812 may at least partially melt. The molten material in asolidification line 802 may fuse with the molten material insolidification line 812 and the molten material in solidification line813 may fuse with the molten material in solidification line 803. Theenergy source and/or laser may also be controlled so that the heatradiating from the solidification line 802 and solidification line 812may cause the thin line of powder between solidification lines 802and/or 803 and solidification lines 812 and/or 813 to sinter togetherwithout melting. Further, the scanning of the energy source and/or laserto form, for example, solidification line 802 and solidification line812 may cause the thin line of powder between the solidification lines802 and/or 803 and solidification lines 812 and/or 813 to remain unfusedwithout sintering and/or melting.

When forming the individual solidification lines 802, 803, 812, and 813,in an example using a laser as the energy source, a galvanometer scannermay guide the laser over a path starting at 701 (FIG. 15) and/or 801(FIG. 16), for example. In the non-limiting embodiment shown in FIG. 15,the laser may then continue subsequently to portions 702, 703, 704and/or 719, 705, 707, 708 and 409. When forming the abovementionedportions, the laser is turned off, defocused and/or decreased in powerin the portions of the path represented by dotted lines (with theexception of the alternative curved solidification portion representedby reference 719 explained further below). For example portions 701,704, 705, 707 and 709 are portions of the path where the laser is turnedoff, defocused and/or decreased in power with relation to the solidportions of the path, so when forming solidification lines within thestripe region bounded by stripe boundaries 747 and/or 748, the laserand/or energy source only supplies enough energy to melt the powderand/or at least partially melt the powder within the stripe region.

The leg elimination patterns shown in FIGS. 12, 14, and 15 may be formedusing the abovementioned laser and/or e-beam path as shown in FIG. 15.In one embodiment, one of or both of the stripes 747 and/or 748 mayeither be an imaginary boundary and/or may be formed as a solidificationline. An energy source (e.g. a laser, e-beam, and/or a plurality oflasers and/or e-beams) may be focused, increased in power and/or turnedon while within the stripe region having stripe boundaries 747 and/or748; accordingly, while a specific stripe region is being formed,solidification lines are only formed within a stripe region bounded bystripe boundaries 747 and 748. When the path of the energy source isscanned outside of the boundaries of the stripe region (e.g. portions701 and 705) the energy source is turned off, defocused and/or decreasedin power so that full melting and solidification does not occur. As analternative, the stripe boundaries 747 and/or 748 may also be at leastpartially melted and solidified by a laser or energy source and formedas solidification lines either before, after, or during a scan andsolidification process within the stripe region.

An exemplary path of the energy source is shown in FIG. 15. When formingthe individual solidification lines (e.g. 702 and 703) of the series ofsolidification lines shown, the energy source may be guided over a pathstarting at 701, and continue subsequently to portions 702, 704, 703,and 705. The energy source may be turned off, decreased in power, and/ordefocused (hereinafter interchangeably referred to as skywriting and/orskywritten) over the path portions designated by reference numbers 701,704, 705, 707 and 709, for example. As an alternative, the galvanometerscanner or other energy source guiding mechanism may also guide theenergy source (e.g. laser) over a path starting at 701, form a firstsolidification line 702 and form a curved solidification portion (anexample of which is shown by reference 719) before forming a secondsolidification line 703. In this alternative, the energy source may forma solidification line 702 and continuously form a curved solidificationportion (an example of which is shown by reference 719) andsolidification line 703. It is noted that while FIG. 15 shows thealternative curved solidification path 719 as a broken line between onlytwo solidification lines, the curved solidification path, such as shownin reference 719 may be formed by the energy source guiding portion foreach subsequent series of solidification lines thereby connecting eachof the solidification lines with a curved solidification path instead offorming a point (e.g. the intersection between solidification lines 702and 703) at the intersection of each set of solidification lines. As yetanother alternative, solidifications lines 702 and 703 may be formedcontinuously without the energy source being turned off, defocusedand/or decreased in power. Forming solidification lines 702 and 703continuously, without any skywriting or without forming a curvedsolidification portion (e.g. 719) between the two solidification lines.This alternative may be most advantageous when the incident anglebetween the each solidification line (e.g. 702 and 703 is sufficientlylarge. In one example, a set of solidification lines (e.g. 702 and 703)are formed continuously, without skywriting (e.g. 704) between the twosolidification lines when the incident angle between the subsequentsolidification lines is greater than 120°. Further, the two segments maybe formed continuously, without skywriting between the twosolidification lines, when the incident angle between the two subsequentsolidification lines is greater than 150°. Further, it is noted thateach of the abovementioned alternative paths (e.g. skywrite 704, curvedsolidification path 719 and/or continuously formed solidification lineswithout a curved solidification path or skywrite between two sets ofangled solidification lines) may be formed either consistentlythroughout the stripe, layer and/or the build, or the abovementionedpaths may be used in any combination either within a stripe, within abuild layer, and/or throughout the build.

As shown in FIG. 15, when the energy source scanning path andsolidification lines are proximal to a portion a third boundary 718(e.g. a contour scan, the end of the component to be built and/or astripe boundary), a third solidification line 706 is formed. The thirdsolidification line 706 may be substantially parallel to a the series ofsolidification lines represented by reference 703. However,solidification line 706, and the subsequent series of solidificationlines may be formed using a substantially linear energy source that doesnot change direction (e.g. segment 706), while at least partiallymelting the powder. In other words, solidification lines 706 are formedfrom a stripe boundary 747 to a solidification line 791 without changingdirection. The remainder of the solidification lines (e.g. 706) may thenbe formed as though solidification line 791 is a stripe boundary.Accordingly, once the scanning strategy switches to the leg eliminationportion of the scan pattern, the energy source skywrites in portion 707when it passes solidification line 791 at point 792, for example. It isnotes that in the abovementioned embodiment using a curvedsolidification portion 719, the line segment 706 may be bounded by thecurved solidification portion 719 such that skywriting occurs once theenergy source path passes the intersection point 706B of the curvedsolidification portion 719 and the segment 706.

It is noted the abovementioned scan pattern is not limited to one energyand/or laser source, and may be performed by a plurality of energyand/or laser sources. For example, a first laser may form solidificationlines 702 and 703, and a second laser may form solidification line 706.

The abovementioned process may be repeated for each subsequent layer.For example, subsequent layer 715 (FIG. 14) may include a stripe regionhaving width 714D which is at least partially filled usingsolidification lines formed parallel with exemplary solidification lines760A and 750A which are formed at an a angle other that 90° withrelation to, and bounded by stripe boundaries of a stripe region.Exemplary solidification lines 760A and 750A two segments that areangled θ₃ with relation to one another. As mentioned above, when thelaser scanning path is proximal to a portion a third boundary (e.g. aboundary other than the stripe boundaries for solidification lines 760Aand 750A), a third series of solidification lines 760B are formed thatare substantially parallel with solidification line 760A. Solidificationlines 760B is formed using a substantially linear laser path (e.g. thepath does not change direction while forming the solidification line)continuing to a solidification line 750A without changing direction.

The abovementioned leg elimination scan strategy may be used incombination with or as an alternative to any of the abovementioned scanstrategies. Further, depending on the geometries and desired propertiesof the component being build using the AM process, each layer mayinclude a plurality of stripe regions, wherein each stripe region isfilled using any one of or combination of the abovementioned strategiesdepending on any one or combination of reasons including, for example: apart geometry, a decrease in build time, to control the heat buildupwithin the powder and/or to increase the efficiency of the build, toimprove and/or control the material properties of the solidifiedmaterial, to reduce stresses in the completed material, and/or to reducewear on the laser, e-beam and/or galvanometer scanner.

In another embodiment, a dwell pattern may be used in combination withor as an alternative to the above mentioned leg elimination strategy, adwell method as shown in FIG. 16, for example, may be used to controlthe heat buildup between each solidification line as well. As anexample, each solidification line may be formed by at least partiallymelting portions 802 and 803 as a first substantially linearsolidification line and a second substantially linear solidificationline respectively. Solidification lines 802 and 803 may be in closeproximity to the next set of formed solidification lines 812 and 813. Inat least one embodiment, if the laser and/or energy source melts thepowder corresponding to each of portions 802, 803, 812, and 814 insuccession, the portions 802, 803, 812, and 813 may fuse together. Asanother example, when forming portions 802, 803, 812, and 813 a laserand/or energy source may adjusted to control the amount of powder meltedalong a solidification line; accordingly, a melting width and depth ofeach solidification line may be controlled. When the laser melts powdercorresponding to solidification line 812, the material in the portion802 may not have cooled and the thin line of powder between the portion802 and the portion 812 may at least partially melt. The molten materialin a solidification line 802 may fuse with the molten material insolidification line 812 and the molten material in solidification line813 may fuse with the molten material in solidification line 803. Theenergy source and/or laser may also be controlled so that the heatradiating from the solidification line 802 and solidification line 812may cause the thin line of powder between solidification lines 802and/or 803 and solidification lines 812 and/or 813 to sinter togetherwithout melting. Further, the scanning of the energy source and/or laserto form, for example, solidification line 802 and solidification line812 may cause the thin line of powder between the solidification lines802 and/or 803 and solidification lines 812 and/or 813 to remain unfusedwithout sintering and/or melting.

An exemplary path of the energy source is shown in FIG. 16. When formingthe individual solidification lines (e.g. 802 and 803) of the series ofsolidification lines shown, the energy source may be guided over a pathstarting at 801, and continue subsequently to portions 802, 804, 803,805, 813, and 812. The energy source may be turned off, decreased inpower, and/or defocused (hereinafter interchangeably referred to asskywriting and/or skywritten) over the path the paths 801, 804, and 805.As an alternative, the galvanometer scanner or other energy sourceguiding mechanism may also guide the energy source (e.g. laser) over apath forming a first solidification line 813 and form a curvedsolidification portion 814 before forming a second solidification line812. In this alternative, the energy source may form a solidificationline 813 and continuously form a curved solidification portion 814 andsolidification line 812. It is noted that while FIG. 16 shows thealternative curved solidification path 814 as a dotted line between onlytwo solidification lines, the curved solidification path, such as shownin reference 814 may be formed by the energy source guiding portion foreach subsequent series of solidification lines thereby connecting eachof the solidification lines with a curved solidification path instead offorming a point (e.g. the intersection between solidification lines 802and 803) at the intersection of each set of solidification lines. As yetanother alternative, solidifications lines 802 and 803 may be formedcontinuously without the energy source being turned off, defocusedand/or decreased in power. Forming solidification lines 802 and 803continuously, without any skywriting within the stripe or withoutforming a curved solidification portion (e.g. 814) between the twosolidification lines. This alternative may be most advantageous when theincident angle between the each solidification line (e.g. 802 and 803 issufficiently large. In one example, a set of solidification lines (e.g.802 and 803) are formed continuously, without skywriting within thestripe (e.g. without skywritten portion 804) between the formation ofthe two solidification lines when the incident angle between thesubsequent solidification lines is greater than 120°. Further, the twosegments may be formed continuously, without skywriting within thestripe boundaries between the two solidification lines, when theincident angle between the two subsequent solidification lines isgreater than 150°. It is noted that each of the abovementionedalternative paths (e.g. skywrite 704, curved solidification path 719and/or continuously formed solidification lines without a curvedsolidification path or skywrite between two sets of angledsolidification lines) may be formed either consistently throughout thestripe, layer and/or the build, or the abovementioned paths may be usedin any combination either within a stripe, within a build layer, and/orthroughout the build.

When forming the individual solidification lines 802, 803, 812, and 813,in an example using a laser, for instance, a galvanometer scanner mayguide the laser over a path starting at 801, and continue subsequentlyto portions 802, 803, 805, 813, and 812. When forming the abovementionedportions, the laser is turned off, defocused and/or decreased in powerin portions 801 and 805 so that when forming solidification lines withinthe stripe region bounded by stripe boundaries 815 and/or 816, the laserand/or energy source only supplies enough energy to the powder to atleast partially melt the powder within the stripe region. It is notedthat all of the abovementioned scan patterns are not limited to oneenergy and/or laser source, and may be performed by a plurality ofenergy and/or laser sources. For example, a first laser maysolidification lines 802 and 803, and a second laser may formsolidification lines 812 and 813.

Depending on at least a geometry of the layer being built and/or astripe boundary. It may be desirable to control the heat buildup withinthe powder and/or in the solidification lines formed on the layer ofpowder using a dwell strategy. For instance, when using the trianglehatch pattern disclosed above, a part boundary or other barrier 820 maybe reached at the end of the stripe region when the forming a series ofsolidification lines (e.g. 802, 803, 812, and 813) within a striperegion bounded by stripe boundaries 815 and 816. As each solidificationline gets shorter near the part boundary or other barrier 820, thepowder which is at least partially melted to form solidification linesmay have insufficient time to cool before the next set of solidificationlines are formed. If insufficient sufficient cooling time between theforming of solidification lines occurs, a high energy density portion830 of the AM build may formed. If the high energy density region, isnot accounted for during a build process by decreasing the amount ofenergy and/or increasing the amount of time during which the energysource is at least partially melting powder, boiling porosity or otherdefects in the completed AM build may occur. As discussed above, onemethod of preventing boiling porosity is to form the solidificationlines in a pattern that minimizes concentrated heat build-up (e.g. theleg elimination strategy discussed above). Another method of preventingexcessive heat buildup is to have the energy source continue on the samepath while the energy source is turned off and/or defocused as describedbelow.

As shown in FIG. 16, solidification lines 802 and 803 may be formed byan energy source path having a length and time t₁. As shown,solidification lines 802 and 803 are formed with the energy source atleast partially melting and forming solidification lines over most ofthe length t₁. When the possibility of a high density region occurs, forexample near a boundary, stripe or other portion of the build 820, thelength and time over which melting occurs is shortened for eachsubsequent segment, and the time and distance over which the energysource follows the path without melting is increased. For example, whenthe solidification lines nearest to portion 830 are formed, the scanningpath remains the same or similar to the scanning length t₁, but theenergy source is primarily not melting and/or partially melting (e.g.over distance t2) and is only melting over a short period of the span(e.g. t3). By increasing the time over which melting is not occurring bycontinuing over substantially the same path, the solidification linesformed closest to portion 830 are allowed to cool sufficiently beforethe next subsequent solidification lines are formed. Thus the heatingand cooling properties of the powder during formation of thesolidification lines near portion 830 can be controlled so as to besimilar to the heating and cooling properties of the powder whensolidification lines 802, 803, 813, and 812 are formed. By employing theabovementioned strategy, improvements in the control of the heat buildupwithin the powder and/or control the material properties of thesolidified material to reduce stresses in the completed material can beachieved. Father, advantages such as reduced wear on the laser, e-beamand/or galvanometer scanner can also be realized.

Because an increase in build time may result using the abovementionedstrategy, the dwell strategy, an example of which is shown in FIG. 16,may be used in combination with any of the abovementioned strategies.For example the dwell strategy may be used at a portion of the buildwhere the abovementioned leg elimination strategy is not practical.Further, the strategy may be used in combination with or as analternative to any of the abovementioned scan strategies for any reason.For instance, depending on the geometries and desired properties of thecomponent being build using the AM process, each layer may include aplurality of stripe regions, wherein each stripe region is filled usingany one of or combination of the abovementioned strategies depending onany one or combination of reasons including, for example: a partgeometry, a decrease in build time, to control the heat buildup withinthe powder and/or to increase the efficiency of the build, to improveand/or control the material properties of the solidified material, toreduce stresses in the completed material, and/or to reduce wear on thelaser, e-beam and/or galvanometer scanner.

In an aspect, the present invention further relates to a method offorming solidification lines and a stripe pattern used in additivemanufacturing techniques which may be of the present inventionincorporated or combined with features of other powder bed additivemanufacturing methods and systems. The following patent applicationsinclude disclosure of these various aspects and their use:

U.S. patent application Ser. No. 15/406,467, titled “AdditiveManufacturing Using a Mobile Build Volume,” with attorney docket number037216.00059, and filed Jan. 13, 2017.

U.S. patent application Ser. No. 15/406,454, titled “AdditiveManufacturing Using a Mobile Scan Area,” with attorney docket number037216.00060, and filed Jan. 13, 2017.

U.S. patent application Ser. No. 15/406,444, titled “AdditiveManufacturing Using a Dynamically Grown Build Envelope,” with attorneydocket number 037216.00061, and filed Jan. 13, 2017.

U.S. patent application Ser. No. 15/406,461, titled “AdditiveManufacturing Using a Selective Recoater,” with attorney docket number037216.00062, and filed Jan. 13, 2017.

U.S. patent application Ser. No. 15/406,471, titled “Large ScaleAdditive Machine,” with attorney docket number 037216.00071, and filedJan. 13, 2017.

The disclosures of these applications are incorporated herein in theirentirety to the extent that they disclose additional aspects of powderbed additive manufacturing methods and systems that can be used inconjunction with those disclosed herein.

This written description uses examples to disclose the invention,including the preferred embodiments, and also to enable any personskilled in the art to practice the invention, including making and usingany devices or systems and performing any incorporated methods. Thepatentable scope of the invention is defined by the claims, and mayinclude other examples that occur to those skilled in the art. Suchother examples are intended to be within the scope of the claims if theyhave structural elements that do not differ from the literal language ofthe claims, or if they include equivalent structural elements withinsubstantial differences from the literal language of the claims.Aspects from the various embodiments described, as well as other knownequivalents for each such aspect, can be mixed and matched by one ofordinary skill in the art to construct additional embodiments andtechniques in accordance with principles of this application.

What is claimed is:
 1. A method for fabricating an object comprising:irradiating at least a portion of a layer of powder, within a firststripe region, to form a first fused region using a first irradiationpattern, wherein forming of the first fused region using a firstirradiation pattern further comprises: forming a first solidificationline, at angle other than 90° with respect to a substantially linearstripe region boundary; forming a second solidification line,intersecting the end of the first solidification line and forming afirst angle other than 0° and 180° with respect to the firstsolidification line; forming a third solidification line, substantiallyparallel to a first solidification line and intersecting the secondsolidification line.
 2. The method of fabricating an object of claim 1,wherein the stripe region boundary is formed by endpoints of the firstsolidification line and adjacent solidification lines.
 3. The method offabricating an object of claim 1, wherein the stripe region boundary isformed as a solidification line.
 4. The method of claim 1, wherein theformation of the first fused region using a first irradiation patternfurther comprises: forming a fourth solidification line, wherein thefourth solidification traverses a stripe region boundary and issubstantially parallel to the first solidification line.
 5. The methodof claim 1, wherein a subsequent layer of powder is provided over thefused region, and at least a portion of the subsequent layer of powder,within a second stripe region, is irradiated to form a second fusedregion using a second irradiation pattern, wherein forming of the secondfused region using a second irradiation pattern further comprises:forming a fourth solidification line, at angle other than 90° withrespect to a substantially linear second stripe region boundary; forminga fifth solidification line, intersecting the end of the firstsolidification line and forming a second angle other than 0° and 180°with respect to the fourth solidification line; forming a sixthsolidification line, substantially parallel to a fourth solidificationline and intersecting the fifth solidification line, wherein the firstangle and second angle are not the same.
 6. The method of claim 1,wherein a subsequent layer of powder is provided over the fused region,and at least a portion of the subsequent layer of powder, within asecond stripe region, is irradiated to form a second fused region usinga second irradiation pattern, wherein forming of the second fused regionusing a second irradiation pattern further comprises: forming a fourthsolidification line at an angle other than 90° relative to the firststripe boundary, forming a fifth solidification line formed at a secondangle other than 0° and 180° with respect to the fourth solidificationline, wherein the first angle and second angle are not the same.
 7. Themethod of claim 1, wherein the powder is irradiated using at least onelaser.
 8. The method of claim 1, wherein the powder is irradiated usingat least one electron-beam.
 9. The method of claim 4, wherein the firstangle and the second angle differ by 10° or more.
 10. The method ofclaim 6, wherein each adjacent layer of the object includes a firstangle and second angle that differ by 10° or more.
 11. The method ofclaim 1, wherein the first irradiation path is further bounded by aplurality of boundary stripes, wherein said plurality of boundarystripes are parallel.
 12. The method of claim 1, wherein the firstirradiation path is further bounded by a second stripe boundary which isparallel to the stripe boundary, wherein the second solidification lineis formed at an angle other than 90° with the second stripe boundary.13. A system comprising an additive manufacturing device for irradiatinga powder, a monitoring device, a computer, and software integratedtogether to adjust irradiation settings in the additive manufacturingdevice, wherein the system irradiates at least a portion of a layer ofpowder, within a first stripe region, to form a first fused region usinga first irradiation pattern, wherein forming of the first fused regionusing a first irradiation pattern further comprises: forming a firstsolidification line, at angle other than 90° with respect to asubstantially linear stripe region boundary; forming a secondsolidification line, intersecting the end of the first solidificationline and forming a first angle other than 0° and 180° with respect tothe first solidification line; forming a third solidification line,substantially parallel to a first solidification line and intersectingthe second solidification line.
 14. The system of claim 13, wherein theformation of the first fused region using a first irradiation patternfurther comprises: forming a fourth solidification line, wherein thefourth solidification traverses a stripe region boundary and issubstantially parallel to the first solidification line.
 15. The systemof claim 13, wherein the system irradiates the powder using a laser. 16.The system of claim 13, wherein the system irradiates the powder usingan electron-beam.
 17. The system of claim 13, wherein the stripeboundary is formed by endpoints of the first solidification line andadjacent solidification lines.
 18. The system of claim 13, wherein thestripe boundary is formed as a solidification line.
 19. The system ofclaim 13, wherein a subsequent layer of powder is provided over thefused region, wherein at least a portion of the subsequent layer ofpowder, within a second stripe region, is irradiated to form a secondfused region using a second irradiation pattern, wherein forming of thesecond fused region using a second irradiation pattern furthercomprises: forming a fourth solidification line, at angle other than 90°with respect to a substantially linear stripe region boundary; forming afifth solidification line, intersecting the end of the firstsolidification line and forming a second angle other than 0° and 180°with respect to the fourth solidification line; forming a sixthsolidification line, substantially parallel to a fourth solidificationline and intersecting the fifth solidification line, wherein the firstangle and second angle are not the same.
 20. The system of claim 13,wherein a subsequent layer of powder is provided over the fused region,wherein at least a portion of the subsequent layer of powder, within asecond stripe region, is irradiated to form a second fused region usinga second irradiation pattern, wherein forming of the second fused regionusing a second irradiation pattern further comprises: forming a fourthsolidification line at an angle other than 90° relative to the firststripe boundary, forming a fifth solidification line formed at a secondangle other than 0° and 180° with respect to the fourth solidificationline, wherein the first angle and second angle are not the same.
 21. Thesystem of claim 20, wherein the second irradiation pattern is furtherbounded by a plurality of stripe boundaries, wherein the plurality ofstripe boundaries are parallel.
 22. The system of claim 21, wherein thefourth solidification line is formed at an angle other than 90° relativeto the plurality of stripe boundaries.
 23. The system of claim 22,wherein the distance between the stripe boundaries forming a boundaryfor the first irradiation pattern and the distance between the stripeboundaries forming a boundary for the second irradiation pattern are notequal.